Hydroelectric power generation apparatus is a system that uses kinetic energy of running water for power generation. The hydroelectric power generation apparatus mainly includes a hydraulic turbine rotated by receiving a flow of water, a power generator coupled to the hydraulic turbine to convert rotational energy into electrical energy, and a control device which controls an output of the power generator and the hydraulic turbine. Optimum power extracted from the power generator varies with flow velocity, and accordingly, the control device measures flow velocity, the hydraulic turbine's rotational speed, or the power generator's power generating voltage, determines optimum power to be extracted from the power generator, and controls the power generator so that an amount of power generated by the power generator matches the optimum value.
Garbage, aquatic plants, branches, cords and other similar debris drifting from upstream and arriving at the power generator get entangled in the hydraulic turbine and cause a reduction in an amount of power generated. For this reason, countermeasures against such debris are important for hydroelectric power generation. For example, it is preferable to install a device upstream of the hydraulic turbine for removing debris.
Japanese Patent Application Laying-Open No. 2013-189837 (Patent Document 1) and Japanese Patent Application Laying-Open No. 2014-202093 (Patent Document 2) disclose techniques for countermeasures against debris obstructing hydroelectric power generation.